1. Field of the Invention
The present invention relates to an insertion instrument having an elongated insertion portion that is inserted into a subject and an operation portion, in which an action portion that acts in accordance with an operation input from the operation portion is provided in the insertion portion.
2. Description of the Related Art
In recent years, an insertion instrument, for example, an endoscope, that is inserted inside a subject or an object has been widely used in the medical field and the industrial field. An endoscope used in the medical field observes an organ inside a body cavity of a subject by inserting an elongated insertion portion into the body cavity. As necessary, the endoscope can perform various kinds of treatment using a treatment instrument that is inserted inside a treatment instrument insertion channel provided in the endoscope.
Further, with an endoscope used in the industrial field, by inserting an elongated insertion portion of the endoscope inside an object such as a jet engine or pipes of a factory, it is possible to carry out an inspection to observe flaws or corrosion or the like at a site to be examined inside the object and perform various repairs.
A configuration is known in which an action portion, for example, a bending portion that is bendable in a plurality of directions, is provided in an insertion portion of an endoscope. The bending portion improves the advancing ability of the insertion portion at a curved section inside a duct, and also varies an observation direction of an observation optical system provided in a distal end portion that is positioned further on a distal end side in the insertion direction (hereunder, referred to simply as “distal end side”) than the bending portion in the insertion portion.
Normally, a bending portion provided in an insertion portion of an endoscope is configured to be bendable in, for example, four directions, namely, upward, downward, left, and right, by connecting a plurality of bending pieces along the insertion direction of the insertion portion. Further, the bending portion is configured to be bendable in any of the upward, downward, left, and right directions by performing a pulling operation from an operation portion with respect to any of four wires that are linear members that are inserted into the insertion portion and which are movable forward and rearward in the insertion direction and whose distal ends are fixed to a bending piece positioned furthest on the distal end side among the bending pieces.
As such a kind of endoscope, for example, Japanese Patent No. 4856289 discloses a configuration in which: a first bending portion and a second bending portion are provided on a distal end side of an insertion portion; the outer circumference of four wires that are inserted through the insertion portion are respectively covered by an inner guide sheath (inner guide pipe) that is a linear member that is movable forward and rearward in an insertion direction; a distal end in the insertion direction of the inner guide sheath is fixed to a distal end of the second bending portion; proximal ends in the insertion direction of the respective inner guide sheaths are configured so as to be simultaneously switchable between a fixed state and a non-fixed state by a fixing switching member (linear member fixing mechanism); the outer circumference of each inner guide sheath is covered by an outer guide sheath (outer guide pipe), respectively; distal ends of the outer guide sheaths are fixed to a distal end of a flexible tube portion; and proximal ends of the outer guide sheaths are fixed at a more rearward position than the proximal end of the flexible tube portion.
According to this configuration, it is possible to cause the first bending portion and the second bending portion to bend in a manner that takes the distal ends of the outer guide sheaths as a starting point by operating a bending operation knob to pull a wire in a state in which a fixed state of the proximal ends of the respective inner guide sheaths has been released. On the other hand, it is possible to cause only the first bending portion to bend in a manner that takes the distal ends of the inner guide sheaths as a starting point by operating the linear member fixing mechanism and performing an operation with respect to the bending operation knob to pull a wire in a state in which the proximal ends of the respective inner guide sheaths are simultaneously in a fixed state. Therefore, the length of the bending portion can be easily varied according to the usage situation, and the insertability of the insertion portion can be improved with a simple configuration.
According to the technology disclosed in Japanese Patent No. 4856289, the linear member fixing mechanism is configured to include a substrate and two moving members that are movable in contacting and separating directions with respect to two faces (top face and bottom face) of the substrate. The linear member fixing mechanism actuates each moving member through a link mechanism, and it is possible to fix the respective inner guide sheaths by each moving members sandwiching the proximal end portions (more specifically, a pipe stopper) of two inner guide sheaths between the moving member and the substrate with a predetermined pressing force, respectively.